FIG. 1 illustrates the network architecture of an Evolved Universal Terrestrial Radio Access (E-UTRAN) composed of evolved Node Bs (eNBs). An eNB functions as an access network and communicates with a User Equipment (UE) via an air interface. There are both a control plane connection and a user plane connection between the UE and the eNB. Each UE attached to the network is served by a Mobility Management Entity (MME), the MME connected with the eNB via a control plane S1 interface (that is, S1 for the control plane, S1-MME). The S1-MME interface provides the UE with a service on the control plane, including mobility management and bearer management functions. An S-GW is connected with the eNB via a user plane S1 interface (that is S1 for the user plane, S1-U), and each UE attached to the network is served by an S-GW. The S1-U interface provides the UE with a service on the user plane, and user plane data of the UE is transmitted between the S-GW and the eNB over an S1-U bearer.
With rapid development of smart terminals and a constantly growing demand of the rate of data services and the capacity of data services required by the users, the conventional macro eNB single-layer coverage network has failed to accommodate such a situation. In view of this, layered network deployment has been introduced in the 3rd Generation Partnership Project (3GPP) so that some eNBs with low power (including femto cellular eNBs, pico eNBs, relays and in other forms) are deployed in a hotspot area, an indoor environment at home, an office environment and other small-coverage environments for an effect of splitting a cell so that an operator can provide the users with services at a higher data rate and a lower cost.
In the conventional layered network as illustrated in FIG. 2, a macro eNB provides underlying coverage, a small eNB with low power (referred in this context to as a local eNB) provides hotspot coverage, there is a data/signaling interface (which may be a wired/wireless interface) between the local eNB and the macro eNB, and the UE may operate while being served by the macro eNB or the local eNB. Due to a small coverage area of a cell controlled by the local eNB, and a small number of UEs served by the local eNB, the UE connected with the local eNB tends to be provided with a better quality of service, e.g., a higher traffic rate, a link with a higher quality, etc. Thus when the UE connected with the macro eNB enters the coverage area of the cell associated with the local eNB, the UE can be handed over to the local eNB to be served by the local eNB; and when the UE is far away from the coverage area of the cell associated with the local eNB, the UE needs to be handed over to a cell controlled by the macro eNB to keep wirelessly connected.
Separation of a user bearer can be supported in the network architecture illustrated in FIG. 2. In the area covered by both the cell of the macro eNB and the cell of the local eNB, the corresponding bearer of the UE can be scheduled and transmitted by the different eNBs. Particularly the network architecture where the user plane is separated from the control plane (CP/UP separation) will be exemplified below. In this approach, when the UE is located in the area covered only by the cell of the macro eNB, both the control plane connection and the user plane connection of the UE are active at the macro eNB, and when the UE moves to/approaches the area covered by both the cell of the macro eNB and the cell of the local eNB, (all or a part of) the user plane bearer connection of the UE is handed over to the local eNB for a higher traffic transmission rate; whereas the control plane connection of the UE remains connected to the macro eNB to thereby lower a signaling overhead due to frequent switching.
In order to enhance mobility management or improve a peak rate in layered network deployment, resources of cells of multiple eNBs may be aggregated for a UE and scheduled separately by the respective eNB. Scheduling is performed with addressing based upon Cell-Radio Network Temporary Identities (C-RNTIs) which identify UEs with Radio Resource Control (RRC) connections in a cell and which are allocated by the respective eNBs in the Long Term Evolution (LTE) system to uniquely identify respective UEs in a cell. Typically when a UE initiates an RRC connection or is being switched, an eNB allocates a dedicated C-RNTI to the UE. The C-RNTI is primarily configured to scramble dynamic scheduling of a Physical Downlink Control Channel (PDCCH) indicator, to scramble an uplink channel, to perform random access and switching procedures triggered by a PDCCH command, etc.
However the Long Term Evolution-Advanced (LTE-A) Release 11 (R11) and earlier versions only support aggregation of carriers served by the same eNB for a UE and allocation of a C-RNTI by the eNB for the UE. In the layered network deployment scenario including a local eNB and a macro eNB, particularly in the architecture where a bearer is separated, carriers/serving cells from different eNBs may be aggregated concurrently for the UE in order to serve the UE. For the different eNBs aggregated for the UE, there has been absent in the prior art a solution to allocation of a C-RNTI to such a UE in this scenario for dynamic scheduling and other procedures.